Glucose and its analogues 2-deoxy-D-glucose (2-DG) and 2-fluoro-deoxy-D-glucose (FDG) are known to be taken up preferentially by cancer cells, a phenomenon that is known as the “Warburg effect”. The positron emission tomography (PET) method makes use of this phenomenon by imaging FDG containing the radioactive fluorine atom 18F. The chemical exchange saturation transfer (CEST) NMR method enables to detect low concentrations of metabolites that contain residues with exchangeable protons such amine, amide or hydroxyl. The enhanced sensitivity of the method allows obtaining images of relatively low concentrations of endogenous cellular components or exogenous agents by MRI.
US 2012/0019245 [1] discloses using CEST MRI to monitor the concentration of various neurotransmitters and energy metabolites to characterize and monitor various disease states in the body, more specifically in the liver, brain and myocardium, correlated to the concentration of that metabolized.
Detection of administered sugar can employ CEST MRI due to the presence of the exchangeable protons in said sugar. WO 2012/082874 [2] discloses methods for MRI for the detection of tissue physiological parameters in a subject by using non-labeled sugar to recognize whether at least one tissue-related parameter is abnormal.
Recently, the CEST MRI method has been shown to enable the imaging of glucose and its analogues with enhanced sensitivity and these compounds were suggested to be used for cancer diagnosis [3,4]. However glucose gives inferior CEST signal due to its rapid conversion to lactic acid by glycolysis, and the two analogues 2-DG and FDG that undergo phosphorylation but do not undergo further metabolism are toxic at high concentrations such as 3 g/kg for 2-DG in rats.